This research proposes a program of clinical investigation and epidemiology that involves postgraduate research and training. The project is centered on a population-based case-control study, nested in a national surveillance registry, which addresses the problem of infection following corneal surgery. Using data from a cohort operated between 1991 and 2004, approximately 250 reported incident cases of postkeratoplasty endophthalmitis will form the study population. At a ratio of 2 controls of each case, matched on date of surgery, approximately 500 individuals will be randomly selected from corneal transplant procedures using donor corneas distributed by US eye banks during this same period. Data will be collected to examine the effect of the duration of donor corneal storage in preservation medium on the risk of endophthalmitis and to explore the possible role of other risk factors, including demographic characteristics and eye-banking variables. Regression analyses will include calculation of relative effect measures with confidence intervals using multivariable modeling that evaluates the relative importance of selected variables while adjusting for cofounders and effect modifiers.